Consider removing usage of DirectByteBuffer and ByteBuffer.allocateDirect

Direct buffers are allocated in native memory instead of java heap
This may lead to unexpected OOM situations described here :

http://monaco.sfbay.sun.com/detail.jsf?cr=4857305
http://monaco.sfbay.sun.com/detail.jsf?cr=4469299

We should avoid usage of direct buffers as much as possible.
Remove the following usages :

PixelUtils.pixelsToImage
ImageFormatTool.RGBtoARGB, RGBtoBGRA
D3DResourceFactory.getBuffer
webnode RTImage.getPixelBuffer